[cidair]

My 550 started to act strange this weekend. No, or very little, boost pressure = very low power and torque! Engine runs smooth, revs all the way to redlineand otherwise acts normal. Check Control says " DRIVETRAIN " not full power available, drive careful, contact BMW Service partner.

Ok, so I contacted my BMW service partner and they found some fault messages in the car memory; loss of boost pressure, boost pressure sensor failure#2, possible defect on wastegate#2, vacuum hose for wastegate faulty.......... there was also a comment on checking that there was a yellow vacuum hose. Yellow? Is this someting that should have been changed on my car?

My first thought was the Hartge ECU, but I recieved a new one that I changed.
No diffrence.

Anyone else had this problem?

[marcielago]

Very sad to hear this. I don't remember hearing any other cases. Been driving my 550i since February, 10K KM, no problems as of yet.

Just asking for our reference. What's your mileage?

[Edman951]

Maybe a boost signal line poped off, so the ecu cut the power.

[tp550i]

any update on repairs and cause?

[0700700]

any update Cidair?

[cidair]

I left my car at Hartge this monday. They checked the ECU and wiring harness ( nothing wrong visually ), and then installed new parts. Same problem! They then removed all tuning parts, including my Supersprint exhaust - still the same problem with the car OEM!
Now the car has been at the BMW workshop for a couple of days, but they still haven´t found what´s causing the loss of boost at low rpm / low speed!?

Different ideas from the diagnosis talks about boost pressure sensor, wastegate, vacuum hose etc etc.

So all credit to Hartge for doing a great job.
I really hope BMW will find the cause soon?

[cidair]

BTW - my car has 32.000km of which 30.000km without a problem.
26.000km has been with the Hartge ECU.

[0700700]

Originally Posted by cidair

BTW - my car has 32.000km of which 30.000km without a problem.
26.000km has been with the Hartge ECU.

Wastegate is a common problem with turbo bmws... i do hope they sort it out soon enough. the 4.4TT engine isnt all that new so they should have some idea of what to do


On a side note, 30000km without a problem isnt really that good, god i miss the days of the old mercedes w124 which would go 300000km without a problem

[cidair]

Problem solved - but it took 1 week of work. The vacuum hoses from the exhaust mufflers was not properly closed, on my Supersprint exhaust. The installation instruction didn´t even say to close the hoses!
Dust and particles was sucked in ( over a period of 20.000km ) and slowly destroyed a valve ( in the trunk ) on the way forward to the engine!!!!
This fooled the ECU to think that there was a problem with the boost pressure and therefore reducing the boost below 4000 rpm ( where the vacuum controlled valve in the OEM exhaust normally openes ). The inconsistance of the problem was caused by the valve sometimes was stuck and sometimes not, due to dust and particles blocking the valve mechanism.

[tp550i]

Glad you found and solved the problem

Everyone with aftermarket exhaust - take note

[cidair]

Really strange that Supersprint sells an exhaust without these vacuum controlled flaps, or don´t mention the importance of closing the loose hoses!

[luigimaster24]

So will this problem keep happening as long as you run the Superspint exhaust on your 550?

[tp550i]

If I understand his description correctly - the problem occured because the factory vacuum hose that controls the stock muffler flap was left un-plugged or "open" after the Supersprint install.

This could occur with any aftermarket muffler that does not make use of the vacuum lines, I don't see that its unique to Supersprint.

This took some time to develop, but anyone running aftermarket mufflers without vacuum operated "flaps" may want to double check that the un-used vacuum lines are appropriately secured (plugged).

[cidair]

Originally Posted by luigimaster24

So will this problem keep happening as long as you run the Superspint exhaust on your 550?

Not if you plug the vacuum hoses properly.